/*
 * Copyright (C) 2009 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package cn.emay.sdk.util.json.gson;

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.lang.reflect.Type;
import java.util.Arrays;
import java.util.Collection;

import cn.emay.sdk.util.json.gson.internal.$Gson$Preconditions;

/**
 * A data object that stores attributes of a field.
 *
 * <p>
 * This class is immutable; therefore, it can be safely shared across threads.
 *
 * @author Inderjeet Singh
 * @author Joel Leitch
 *
 * @since 1.4
 */
public final class FieldAttributes {
	private final Field field;

	/**
	 * Constructs a Field Attributes object from the {@code f}.
	 *
	 * @param f
	 *            the field to pull attributes from
	 */
	public FieldAttributes(Field f) {
		$Gson$Preconditions.checkNotNull(f);
		this.field = f;
	}

	/**
	 * @return the declaring class that contains this field
	 */
	public Class<?> getDeclaringClass() {
		return field.getDeclaringClass();
	}

	/**
	 * @return the name of the field
	 */
	public String getName() {
		return field.getName();
	}

	/**
	 * <p>
	 * For example, assume the following class definition:
	 * 
	 * <pre class="code">
	 * public class Foo {
	 * 	private String bar;
	 * 	private List&lt;String&gt; red;
	 * }
	 *
	 * Type listParameterizedType = new TypeToken&lt;List&lt;String&gt;&gt;() {
	 * }.getType();
	 * </pre>
	 *
	 * <p>
	 * This method would return {@code String.class} for the {@code bar} field and
	 * {@code listParameterizedType} for the {@code red} field.
	 *
	 * @return the specific type declared for this field
	 */
	public Type getDeclaredType() {
		return field.getGenericType();
	}

	/**
	 * Returns the {@code Class} object that was declared for this field.
	 *
	 * <p>
	 * For example, assume the following class definition:
	 * 
	 * <pre class="code">
	 * public class Foo {
	 * 	private String bar;
	 * 	private List&lt;String&gt; red;
	 * }
	 * </pre>
	 *
	 * <p>
	 * This method would return {@code String.class} for the {@code bar} field and
	 * {@code List.class} for the {@code red} field.
	 *
	 * @return the specific class object that was declared for the field
	 */
	public Class<?> getDeclaredClass() {
		return field.getType();
	}

	/**
	 * Return the {@code T} annotation object from this field if it exist; otherwise
	 * returns {@code null}.
	 *
	 * @param annotation
	 *            the class of the annotation that will be retrieved
	 * @return the annotation instance if it is bound to the field; otherwise
	 *         {@code null}
	 */
	public <T extends Annotation> T getAnnotation(Class<T> annotation) {
		return field.getAnnotation(annotation);
	}

	/**
	 * Return the annotations that are present on this field.
	 *
	 * @return an array of all the annotations set on the field
	 * @since 1.4
	 */
	public Collection<Annotation> getAnnotations() {
		return Arrays.asList(field.getAnnotations());
	}

	/**
	 * Returns {@code true} if the field is defined with the {@code modifier}.
	 *
	 * <p>
	 * This method is meant to be called as:
	 * 
	 * <pre class="code">
	 * boolean hasPublicModifier = fieldAttribute.hasModifier(java.lang.reflect.Modifier.PUBLIC);
	 * </pre>
	 *
	 * @see java.lang.reflect.Modifier
	 */
	public boolean hasModifier(int modifier) {
		return (field.getModifiers() & modifier) != 0;
	}

	/**
	 * This is exposed internally only for the removing synthetic fields from the
	 * JSON output.
	 *
	 * @return true if the field is synthetic; otherwise false
	 * @throws IllegalAccessException
	 * @throws IllegalArgumentException
	 */
	Object get(Object instance) throws IllegalAccessException {
		return field.get(instance);
	}

	/**
	 * This is exposed internally only for the removing synthetic fields from the
	 * JSON output.
	 *
	 * @return true if the field is synthetic; otherwise false
	 */
	boolean isSynthetic() {
		return field.isSynthetic();
	}
}
